Muñoz Abella, María BelénMontero García, LauraRubio Herrero, PatriciaRubio Ruiz de Aguirre, María Lourdes2023-04-242023-04-242022-12-02Muñoz-Abella, B., Montero, L., Rubio, P., & Rubio, L. (2022). Determination of the Critical Speed of a Cracked Shaft from Experimental Data. Sensors, 22(24), 9777.1424-3210https://hdl.handle.net/10016/37184This article belongs to the Section Fault Diagnosis & Sensors.In this work, a procedure to obtain an accurate value of the critical speed of a cracked shaft is presented. The method is based on the transversal displacements of the cracked section when the shaft is rotating at submultiples of the critical speed. The SERR (Strain Energy Ralease Rate) theory and the CCL (Crack Closure Line) approach are used to analyse the proposed methodology for considering the behaviour of the crack. In order to obtain the best information and to define the procedure, the orbits and the frequency spectra at different subcritical rotational speed intervals are analyzed by means of the Fast Fourier Transform. The comparison of the maximum values of the FFT peaks within the intervals allows the subcritical speed to be determined, along with the value of the critical speed. When verified, the proposed procedure is applied to shafts with the same geometry and material and with cracks of increasing depth. The results show that the critical speed diminishes with the severity of the crack, as expected. A comparison is made between the critical speed obtained using the vertical and the horizontal displacements, finding no remarkable differences, meaning that in practical applications only one sensor for one of the displacements (in the vertical or horizontal direction) is needed to determine the critical speed. This is one of the main contributions of the paper, as it means that the orbits of the shaft are not needed. Finally, after this study we can conclude that the best results are achieved when the critical speed is obtained using data displacement in only one direction within the intervals around 1/2 or 1/3 of the critical speed.22eng© 2022 by the authors.Atribución 3.0 EspañaCracked shaftsCritical speedFrequency spectrumRotating shaftsresearch articleFísicaIngeniería Mecánicahttps://doi.org/10.3390/s22249777open access124, 977722Sensors22AR/0000032303